Modern global cellular and non-cellular positioning technologies are based on generating large global databases containing information on cellular and non-cellular signals. The information may originate entirely or partially from users of these positioning technologies acting as data collectors.
The data provided by these data collectors is typically in the form of “fingerprints”, which contain a position that is estimated based on, e.g., received satellite signals of a global navigation satellite system (GNSS) and measurements taken from one or more radio interfaces for signals of a cellular and/or non-cellular radio network. In the case of measurements on cellular signals, the results of the measurements may contain a global and/or local identification of the cellular network cells observed, their signal strengths and/or pathlosses and/or timing measurements like timing advance (TA) or round-trip time (RTT). For measurements on wireless local area network (WLAN) signals, as an example of signals of a non-cellular network, the results of the measurements may contain a basic service set identification (BSSID), like the medium access control (MAC) address of observed access points, and/or the service set identifier (SSID) of the access points, and/or the signal strength of received signals (received signal strength indication RSSI or physical Rx level in dBm with a reference value of 1 mW, etc.), and/or pathloss estimates and/or timing measurements (like e.g. RTT).
This data may then be transferred to a server or cloud, where the data (usually of a multitude of users) may be collected and where positioning-related information may be generated (or updated) based on the data. Such positioning-related information for instance comprise estimates for respective coverage areas (coverage area estimates) and/or radio channel models for communication network cells or nodes. Positioning-related information may for instance serve as a “radiomap”.
In the end, this positioning-related information may be used for estimating the position of mobile terminals. This may function in two modes. The first mode is the terminal-assisted mode, in which the mobile terminal performs the measurements of the cellular and/or non-cellular air interface, provides the measurements (e.g. at least an identification of the cells observed) to the remote server, which in turn, based on the positioning-related information and the measurements, determines and provides the position estimate back to the mobile terminal. The second mode is the terminal-based mode, in which the mobile terminal has a local copy of the positioning-related information (or only a subset thereof, e.g. a regionally restricted subset thereof). This subset copy is downloaded by the mobile terminal from a remote server for the area of interest (e.g. a small area around the current location, for a whole country, or so). This subset copy can of course be pre-installed to the mobile terminal in the factory, but even in that case the data needs to be refreshed at some point.